The U.S. federal prison system was placed on lockdown nationwide following a deadly incident at a Texas prison, officials said Monday. “Multiple inmates were observed fighting at the United States Penitentiary Beaumont” in Texas, said the Federal Bureau of Prisons in a news release. Prison staff then “immediately secured the area” but found inmate Guillermo Riojas and inmate Andrew Pineda with life-threatening injuries, prison officials said. They were transported to a nearby hospital, where they were both pronounced dead, the bureau said. Meanwhile, it added, “Two additional inmates were transported to a local hospital for further medical assessment and treatment.” Due to the incident, which was not described in detail by the Bureau of Prisons, the entire federal prison system was placed on temporary lockdown. The agency said in a statement that it was acting out of an “abundance of caution” and facilities would be locked down as “a temporary measure …